On 03/25/2018 11:17 AM, Chris Angelico wrote:
> On Sun, Mar 25, 2018 at 8:37 PM, Jugurtha Hadjar
> <jugurtha.hadjar at gmail.com> wrote:
>> On 03/24/2018 07:14 PM, D'Arcy Cain wrote:
>>> class C1(dict):
>>> class C2(object):
>>> def f(self):
>>> return X['field']
>>>
>>> O1 = C1()
>>> O1['field'] = 1
>>> O2 = O1.C2()
>>> print(O2.f())
>>
>> I prefer to *feed* the child to the parent or vice versa.
> Congrats, this ranks on my list of "creative people who sound like
> psycho murderers". Digital artists and cooks tend to rank fairly
> highly on that list.
Given that without prior knowledge, Python may suggest a satirical show
or a huge snake, I'm right at home as either creative or a psycho.
>> class C1(object):
>> def __init__(self):
>> self.child = None
>> class C2(object):
>> def __init__(self, parent=None):
>> self.parent = parent
> The trouble with this is that there's fully-constructed objects with
> no parent-child relationships. Why should you have a two-step
> construction process? It makes a LOT more sense to simply require a
> parent on construction, rather than feeding one to the other in a
> post-construction assignment. And if you remove the default here, your
> suggestion isn't materially different from what's already been posted.
>
Right, I see.. What do you think about something like this:
<----------------------------------------------------------------------->
class C2(object):
def __init__(self, parent=None):
self.parent = parent
def foo(self):
print("I am {self.__class__.__name__} foo".format(self=self))
self.parent.foo()
class C1(object):
def __init__(self, child_class=None):
self.child = child_class(parent=self)
def foo(self):
print("I am {self.__class__.__name__} foo".format(self=self))
c1 = C1(child_class=C2)
c1.child.foo() # I am C2 foo
# I am C1 foo
<------------------------------------------------------------------------>
Check my logic: The reason I'm going through these contortions is to
allow the user to choose which child class to use instead of hard coding
C2 inside C1, hence the psycho feeding/injecting of C2 in C1. I can
delay making a choice and I can even postpone it to run-time (say I have
a web-page with a menu that asks which child class I want to use, I can
select C2, or C1 and I'll have the instance created with my choice).
Does this make sense and is there a more succinct way to do it this way?
--
~ Jugurtha Hadjar,